From 53e254b7151df0521b834c34e2f94c49831186bc Mon Sep 17 00:00:00 2001
From: Matias Manevi <manevimatias@ekumenlabs.com>
Date: Fri, 14 Nov 2025 10:02:20 -0800
Subject: [PATCH] Generate `using` declarations for anonymous structs in WASM
 bindings.

PiperOrigin-RevId: 832359379
Change-Id: Ie5913c584c5605f512dbe423524a829043179b6f
---
 wasm/codegen/generated/bindings.cc |  5 ++---
 wasm/codegen/generators/structs.py | 11 +++++++++++
 wasm/codegen/templates/bindings.cc |  8 +-------
 3 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/wasm/codegen/generated/bindings.cc b/wasm/codegen/generated/bindings.cc
index 2dcc0132..c7939ede 100644
--- a/wasm/codegen/generated/bindings.cc
+++ b/wasm/codegen/generated/bindings.cc
@@ -105,13 +105,12 @@ std::vector<WrapperType> InitWrapperArray(ArrayType* array, SizeType size) {
   return result;
 }
 
-// Create the types for anonymous structs
 using mjVisualGlobal = decltype(::mjVisual::global);
-using mjVisualQuality = decltype(::mjVisual::quality);
 using mjVisualHeadlight = decltype(::mjVisual::headlight);
 using mjVisualMap = decltype(::mjVisual::map);
-using mjVisualScale = decltype(::mjVisual::scale);
+using mjVisualQuality = decltype(::mjVisual::quality);
 using mjVisualRgba = decltype(::mjVisual::rgba);
+using mjVisualScale = decltype(::mjVisual::scale);
 
 struct MjContact {
   explicit MjContact(mjContact *ptr);
diff --git a/wasm/codegen/generators/structs.py b/wasm/codegen/generators/structs.py
index 5c09e8c7..aa1fe966 100644
--- a/wasm/codegen/generators/structs.py
+++ b/wasm/codegen/generators/structs.py
@@ -699,6 +699,17 @@ class Generator:
     autogenned_struct_definitions = []
     markers_and_content = []
 
+    typedefs = []
+    for type_name in sorted(constants.ANONYMOUS_STRUCTS):
+      s = constants.ANONYMOUS_STRUCTS[type_name]
+      typedefs.append(
+          f"using {type_name} = decltype(::{s['parent']}::{s['field_name']});"
+      )
+    markers_and_content.append((
+        "// {{ ANONYMOUS_STRUCT_TYPEDEFS }}",
+        typedefs,
+    ))
+
     # Sort by struct name by dependency to ensure deterministic output order
     sorted_struct_names = sort_structs_by_dependency(self.structs_to_bind_data)
 
diff --git a/wasm/codegen/templates/bindings.cc b/wasm/codegen/templates/bindings.cc
index 1de0922e..6e1494e9 100644
--- a/wasm/codegen/templates/bindings.cc
+++ b/wasm/codegen/templates/bindings.cc
@@ -105,13 +105,7 @@ std::vector<WrapperType> InitWrapperArray(ArrayType* array, SizeType size) {
   return result;
 }
 
-// Create the types for anonymous structs
-using mjVisualGlobal = decltype(::mjVisual::global);
-using mjVisualQuality = decltype(::mjVisual::quality);
-using mjVisualHeadlight = decltype(::mjVisual::headlight);
-using mjVisualMap = decltype(::mjVisual::map);
-using mjVisualScale = decltype(::mjVisual::scale);
-using mjVisualRgba = decltype(::mjVisual::rgba);
+// {{ ANONYMOUS_STRUCT_TYPEDEFS }}
 
 // {{ AUTOGENNED_STRUCTS_HEADER }}